The aim of this work is to study the applications of Monte Carlo simulation technique for the SPECT cardiac imaging for the purpose of diagnosis and early detection of heart disease (i.e. calcification, tumors and heart malfunction). We used the versatile Monte Carlo simulation toolkit Geant4 in order to mimic the interaction of particles with a given mathematical human body model. As a case study, we investigated the imaging of the High-Definition Reference Korean-Man (HDRK-Man) voxel model which its specific data was provided by the Korean team. The voxel model, adjusted to the Reference Korean Man, is in height and 68 kg in weight and composed of ∼30 million voxels whose size is . We implemented a Geant4-based program for that purpose through the utilization of specific classes, as it was written in C++ language, namely the “G4VNestedParameterisation” class, the generation of primary particles randomly from the heart organ zone, in order to simulate the uniform distribution of the inserted radio-pharmaceutical Technetium-99m (99mTc) emitter of photons with mean energy of . Rotating the sensitive detector, representing the gamma camera, around the phantom (voxel model) with specific step angles covering the 360º studied area, we record multiple simulated files as the simulation output containing the interacted particle position within the detector and its deposited energy. Output data was then transformed into a digital image with given dimensions in the form of ascii files using a home coded program written in C++ for that purpose.